Sprinkler base



FIG. 1 is a top perspective view of an embodiment of the claimed design;

FIG. 2 is a front view thereof;

FIG. 3 is a rear view thereof;

FIG. 4 is a left side view thereof;

FIG. 5 is a right side view thereof;

FIG. 6 is a top view thereof; and,

FIG. 7 is a bottom view thereof.

Any portion of the article depicted in broken lines forms no part of the claimed design.

Broken lines formed by equal length dashes show unclaimed subject matter. 

CLAIM The ornamental design for a sprinkler base, as shown and described. 